Surgical dilator, retractor and mounting pad

ABSTRACT

A retractor having an elongate body that provides access to a surgical location within a patient. The elongate body includes a plurality of segments that are connected to one another through a plurality of ratcheting mechanisms. The ratcheting mechanisms permit relative movement of the segments with respect to one another when expander dilators are inserted within the retractor. The segments are surrounded and retained by a resilient elastomeric sleeve or bands. The distal end surfaces of the segments include thin edges that are configured to mobilize, dissect, split and retract the terminal tissues in the surgical area. The retractor is used in conjunction with a resilient elastomeric pad that is affixed to the patient and firmly engages the outer surface of the elongate body to thereby anchor the retractor to the patient. A separate anchoring device can be used to connect the retractor to the pad.

CROSS-REFERENCE TO RELATED APPLICATIONS

In accordance with 37 C.F.R. §1.76, a claim of priority is included inan Application Data Sheet filed concurrently herewith. Accordingly, thepresent invention claims priority as a divisional of U.S. patentapplication Ser. No. 12/541,617, filed Aug. 14, 2009, entitled “SurgicalDilator, Retractor and Mounting Pad”, which application is acontinuation-in-part of U.S. patent application Ser. No. 12/393,352,filed Feb. 26, 2009, entitled “Retractor and Mounting Pad”, the entirecontents of which are hereby expressly incorporated by reference.

FIELD OF THE INVENTION

The present system and method relate to devices and methods forperforming percutaneous surgeries, and in particular, to a less invasiveaccess portal for use in orthopedic spinal surgery.

BACKGROUND OF THE INVENTION

Open spinal surgical procedures generally require a relatively longincision, extensive muscle stripping, prolonged retraction of tissues,and increase risk of damage to vascular and nerve tissue. This type ofprocedure usually necessitates many weeks of post-operative recovery dueto the use of long hours under general anesthesia, blood transfusionsand the unavoidable trauma caused to the body tissues during theprocedures. An open surgical procedure will also result in significantpermanent scarring leading to fusion disease.

Surgery performed percutaneously has achieved major improvements overopen surgery. The reduction of muscle and tissue dissectionsignificantly reduces post operative recovery, pain, and recovery time.Percutaneous surgery is particularly beneficial for spinal surgerybecause the surgical area is deep within the body and in locationssurrounded by sensitive and critical body tissues. Tube retractors havebeen developed to provide minimally invasive access to the surgicalarea. The ability to dilate muscle tissue, as opposed to strip or detachthem from the bony anatomy, will reduce the damage and risks normallyassociated with the open type surgery.

The typical tube retractor technique starts with the identification ofthe correct entry point, establishing the trajectory from the skin tothe pathology to be addressed and the corresponding skin incision. Theinitial soft tissue dilator is inserted through the incision andforcefully advanced to the objective site. A series of larger dilatorsare inserted over the initial dilator thereby sequentially increasingthe diameter until the final/operative dilator is inserted. Once theoperative dilator is in place it must be fixed in order to resistmovement that will result from forces imposed by the patient's tissue.Currently, the accepted approach to fixation is a point outside of thepatient's anatomy. Typically a rigid arm is attached at one end to theretractor while the opposite end of the arm is attached to a bed railclamp. Once the retractor is fixed in position, the surgeon begins theoperation to address the pathology. Upon completion of the procedure theretractor tube is removed and the skin incision is closed. Because ofthe reduced morbidity to the patient, the patient's initial recoverytime should be less, blood loss should be less, operating room timeshould be less, anesthesia time should be less, patient stay in thehospital should be less, return to work time should be less and theoverall cost of the procedure should be less.

One of the most difficult aspects of the current technique is that therigid fixation of the retractor is sometimes subject to unintentional orunavoidable movement of the patient during the course of the surgicalprocedure. Another consistent problem is the inability of the currentdesigns and methods to adequately retract the muscle tissue at thedistal end of the retractor, which for all intents and purposes is themost crucial portion of the retractor. Due to the retractors inabilityto clear the surgical area the surgeon must resort to cutting,cauterizing and removing the final fibers of muscle. This process ofphysical tissue removal carries with it increased risk of damage toancillary tissues and nervous tissues, while at the same time increasingmorbidity, blood loss and operative time. These difficulties result inhigh levels of frustration making the technique less likely to beadopted by the majority of surgeons. The current retractors lack thedistraction capability at the distal end of the retractor which is wherethe strongest forces resisting the retractor are present. In additionthe current retractor designs do not accommodate the natural anatomicalshape of the patient's anatomy where the pathology exists.

DESCRIPTION OF THE PRIOR ART

Retractors for use in percutaneous spinal surgery lack the ability toeasily efficiently and clearly access the surgical area. Likewise, theydo not have a simple, effective and efficient device to anchor theretractor relative to the patient.

U.S. Pat. No. 5,460,170 discloses an adjustable, expandable retractorsuitable for use in small surgical incisions or punctures. The device isable to expand the incision or puncture to one or more enlargedcross-sectional areas and designed to protect the edges of the incisionor puncture. The surgical retractor comprises a radially expandabletubular body having a control at the proximal end. Pull wires couple thecontrol to the tubular body such that force applied to the control istransmitted to the tubular body as axially compressive force.

U.S. Pat. No. 3,788,318 discloses an expandable tube, referred totherein as a cannula, is formed by arranging at least one sheet of thinflexible material to form a tube while providing teeth or the like onthe interengaging surfaces to permit controlled expansion of the tube byadjusting the surfaces over one another.

U.S. Pat. No. 6,187,000 discloses a cannula with an expandable portionfor enabling an increase in the cross-sectional area of the passage atthe distal end. The expandable portion of the tube structure, whenexpanded, has a conical configuration.

U.S. Pat. No. 6,652,553 discloses a surgical tool for use in expanding acannula and includes a first leg having a first end engageable with aninner surface of the cannula. A second leg is connected with the firstleg. The second leg has a second end engageable with the inner surfaceof the cannula. The first and second ends are movable away from eachother to apply a radially outwardly directed force to the inner surfaceof the cannula and cause expansion of the cannula.

U.S. Pat. No. 7,261,688 discloses a retractor having a working channelformed by a first portion coupled to a second portion. The first andsecond portions are movable relative to one another from an unexpandedconfiguration to an expanded configuration to increase the size of theworking channel along the length thereof.

U.S. Pat. Nos. 6,524,320 and 7,144,393 disclose a cannula having anexpandable portion for enabling an increase in the cross-sectional areaof the passage. The expandable portion of the tubular structure has aslot and a guide member disposed in the slot. The guide member ismovable from a first end of the slot toward a second end of the slot toenable the cross-sectional area of the passage to increase. Theexpandable portion has a stop between the first and second ends of theslot engageable with the guide member to retain the guide member in aposition relative to the slot and resist movement of the guide memberfrom the position relative to the slot. In the '393 patent, theexpandable portion has a contracted condition in which thecross-sectional area of the distal end of the passage has a firstcross-sectional area. The expandable portion has an expanded conditionin which the distal end of the passage has a second cross-sectional areagreater than the first cross-sectional area. The second cross-sectionalarea is greater than a cross-sectional area of the proximal end of thepassage when the expandable portion is in the expanded condition. Aretaining mechanism resists movement of the expandable portion from theexpanded condition toward the contracted condition during the surgicalprocedure. The retaining mechanism is released at the conclusion of thesurgical procedure to permit movement of the expandable portion from theexpanded condition toward the contracted condition for removal of thestructure. The expandable sleeve is provided with a lockable means inthe expanded position.

U.S. Pat. Nos. 7,179,225 & 7,221,451 disclose a retractor that has anelongate body and an expandable shroud. The elongate body has an outersurface and an inner surface partially defining a passage. The elongatebody also has a first longitudinal edge and a second longitudinal edge.The elongate body is capable of having an enlarged configuration wheninserted within the patient. In the enlarged configuration the firstlongitudinal edge is spaced apart from the second longitudinal edge. Theexpandable shroud is configured to extend from the first longitudinaledge to the second longitudinal edge when the first and second edges arespaced apart. The shroud partially defines the passage. Thecross-sectional area of said passage at a first location is greater thanthe cross-sectional area of the passage at a second location, whereinthe first location is distal to the second location. See FIG. 70 in the'225 patent and FIG. 71 for oval and oblong shape.

U.S. Pat. No. 7,223,233 discloses methods and devices for illuminating asurgical space in a patient. A retractor provides a portal or workingpath for access to a working space location in the patient. Theretractor transmits and emits light from a light delivery system toilluminate the working channel and surgical space.

U.S. Publication No. 2006/0041270 discloses an expandable sheath that isinsertable into a patient through an incision. Once inserted andadvanced to the target surgical site, the sheath can be expanded to anenlarged diameter. The wall of the sheath is fabricated from a tubularstructure comprising filamentous elements that extend axially and atleast partially circumferentially along the length of the sheath. Thetubular filamentous material is drawn or expanded axially to create thesmall diameter configuration that is inserted into the patient. Astandoff attaches the distal end of the tubular filamentous material tothe sheath hub by way of radially movable anchors. Additionalfilamentous tubular material extends out the proximal end of the hub. Acompression mechanism forces the additional filamentous tubular materialin the distal direction which causes axial compression and radial ordiametric dilation of the working length of the sheath, that part of thesheath that extends beyond the proximal end of the hub. Radial dilationis accomplished with no substantial change in sheath working length.

U.S. Publication No. 2006/0200023 discloses systems and methods includean anchor engageable to a vertebra and an extender removably mounted tothe anchor. The extender includes an insulating member extending atleast partially thereabout to electrically insulate the extender andprevent shunting of electrical signals delivered through the extender tothe anchor to structures adjacent the extender. Flexible jacket 26includes a means for monitoring nerves.

U.S. Publication No. 2008/0234550 discloses a less invasive access portfor use in minimally invasive surgery allows for manipulation of theviewing angle into the working site in a transverse plane. According toone exemplary embodiment, the less invasive access port is designed tominimize the need for muscle retraction. Additionally, the less invasiveaccess portal provides sufficient light, irrigation, suction and spacefor sundrymedical instruments. According to one exemplary embodiment, aless invasive access port device includes a retractor assembly havingfour retractor blades secured in various positions by pins placed withinslots on the retractor blades. A cannula includes integrated interfacesfor light, irrigation and suction. A housing forms a collar around a topof the cannula and houses the light, irrigation and suction mechanisms.Instruments and implants may be passed through the cannula and into theworking space created by the retractor assembly. Visualization of theworking site can be attained under direct vision.

SUMMARY OF THE INVENTION

The present invention is directed to methods and devices for performingpercutaneous, minimally invasive spinal surgery. In particular theinvention includes a percutaneous tissue retraction device that providesaccess to the surgical area within the patient. Another aspect of theinvention includes a device for anchoring the retractor device directlyon the patient without the aid of additional structural elements toaffix the retractor to other objects within the operating room such asthe operating table.

The current retractor addresses the current problem making itsutilization more reproducible, easier to learn and visualize andincreases safety while delivering a more consistent result.

The anchoring device includes a pad that is affixed to the patient.Should the patient move slightly, intentionally or unintentionally, theretractor maintains the same tissue retraction and the same trajectory.This provides an accurate and stable portal to the patient's pathology.The pad eliminates the necessity for rigid fixation to a point outsideof the field of operation or to an independent immobile point such as abed rail. The rigid fixation device is metallic and used withconventional metallic split blade retractors that reduce visualizationof the approach through the retractor as well as the visualization ofthe objective site while using operative fluoroscopy.

The anatomical shape of the distal end of the current retractor producesa significantly improved ability to mobilize, dissect, split and retractthe terminal tissues of the psoas muscle at the point on the spine wherethe entry is to be made. Current distal end designs are parallel to thespine and do not comply with the natural shape of the spine.

The ovoid shape of the retractor requires less retraction in twodifferent planes while achieving adequate exposure thereby making theprocedure easier and more reproducible.

Likewise, the anatomical shape of the distal end of the dilator wheninserted safely and gently, divides/splits the psoas muscle fibers alongthe longitudinal plane of the spine. The distal end shape of the dilatormobilizes and dissects the muscle fibers more effectively and whensubsequently rotated ninety degrees provides a dilator that will safelyand gently sweep the terminal fibers in order to enable consistentretraction of the muscle fibers while the retractor is inserted. Thefinal dilator is unique in its ability to create a path for theretractor which complies with the patient's anatomy in a safe, gentlefashion allowing for efficient mobilization of the muscle fibers andmaintaining the muscle retraction when inserting the retractor. Currentsystems use round dilators with flat bottom surfaces. When the retractoris inserted over the final dilator and the dilator is removed, musclefibers creep under the end of the retractor and the doctor must then useinstruments to sweep the fibers out of the way, under the blades orablate them.

Accordingly, it is an objective of the instant invention to provide aretractor for performing minimally invasive spinal surgery that providesimproved access to the surgical area.

It is a further objective of the instant invention to provide aretractor device that the surgeon will find more intuitive to use owingto its construction ease of use.

It is yet another objective of the instant invention to provide aretractor for minimally invasive spinal surgery with an anatomicallyshaped distal end resulting in a much improved ability to mobilize,dissect, split and retract the terminal tissues of the psoas muscle atthe point of the spine where the entry is to be made.

It is a still further objective of the invention to provide a retractorwhere the walls of the retractor apply an opening force throughout thelength of the retractor and provide a more robust retraction.

It is a still further objective of the invention to provide aradiolucent retractor for greater visualization during the surgicalprocedure.

Other objects and advantages of this invention will become apparent fromthe following description taken in conjunction with any accompanyingdrawings wherein are set forth, by way of illustration and example,certain embodiments of this invention. Any drawings contained hereinconstitute a part of this specification and include exemplaryembodiments of the present invention and illustrate various objects andfeatures thereof.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a top view of the retractor showing the retractor segments andthe encircling elastomeric sleeve.

FIG. 2 is a schematic showing the four segments of the retractor.

FIG. 3 is enlarged top sectional view of two of the segments andratcheting mechanism on each of the segments within the circled area ofFIG. 2.

FIG. 4 is an enlarged top partial sectional view showing theinterengaging teeth of the ratcheting mechanism on each of the segmentsand the surrounding elastomeric sheath within the circled area of FIG.3.

FIG. 5 is a front view of the interior surface of one of the semicylindrical members showing four discrete locations for the teeth whichform part of the ratcheting mechanism.

FIG. 6 is a front view of the interior surface of one of the semicylindrical showing a continuous set of teeth that run the length of thesegment from the proximal to the distal end portions.

FIG. 7 is a side view of the exterior surface of one of the semicylindrical segments.

FIG. 8 is a front view of the exterior surface of one of the semielliptical segments.

FIG. 9 is a side view of the exterior surface of one of the semielliptical segments.

FIG. 10A is a side view of a patient with their side in an upwardposition and patient pad and retractor in place.

FIG. 10B is a top view of the patient pad with the initial incision.

FIG. 11A is a top view of the tool that is used to rotate the finaloperative dilator as well as the retractor.

FIG. 11B is a side view of the tool that is used to rotate the finaloperative dilator as well as the retractor.

FIGS. 12A and 12B illustrate the initial dilators.

FIGS. 12C, 12D, 12E and 12 F illustrate various views of the oblongfinal operative dilator.

FIG. 12G is an example of a retractor expansion dilator.

FIG. 13 is a top view of the retractor in position on the patient.

FIG. 14A is a top view of the retractor in position within the patient'sbody.

FIG. 14B is a side view of the retractor positioned within the patient'sbody.

FIG. 15 is a top view of the retractor in position within the patient'sbody after being rotated ninety degrees

FIG. 16A is a top view of the retractor in position within the patient'sbody after being rotated ninety degrees.

FIG. 16B is a side view of the retractor positioned within the patient'sbody after being rotated ninety degrees.

FIGS. 17A and 17B diagrammatically show the spatial relationship betweenthe retractor segments, with FIG. 17B showing the expanded condition.

FIG. 18A, is a perspective view of an alternative oblong final dilator.

FIG. 18B is a perspective view of the distal end of the final dilator ofFIG. 18A.

FIG. 18C is a top view of the final dilator shown in FIG. 18A

FIG. 18D is a bottom view of the final dilator shown in FIG. 18A.

FIG. 19A is a perspective view of another alternative embodiment for theoblong final operative dilator.

FIG. 19B is a perspective view of the distal end of the final operativedilator shown in FIG. 19A.

FIG. 19C is a perspective side view of the final operative dilator shownin FIG. 19A.

FIG. 19D is a top view of the final operative dilator shown in FIG. 19A.

FIG. 19E is a bottom view of the final operative dilator shown in FIG.19A.

FIG. 20 is a perspective view of an alternative embodiment of theadjustable retractor.

FIG. 21 is a top view of the retractor shown in FIG. 20 with theretractor in its most compact configuration

FIG. 22 is a top view of the retractor shown in FIG. 20 with a retractordilator expanding the retractor an intermediate expanded configuration.

FIG. 23 is a top view of the retractor shown in FIG. 20 with theretractor in an intermediate position between most compact and mostexpanded configuration.

FIG. 24 is a top view of the retractor of FIG. 20 with a retractordilator urging the retractor to the most expanded configuration.

FIG. 25 is a perspective top view the retractor, the patient pad and adevice to anchor the retractor to the patient pad.

FIG. 26 is a top perspective view an alternative arrangement foranchoring the retractor to the patient pad.

FIG. 27 is a side perspective view of another alternative embodiment toanchor the retractor to the patient pad.

FIG. 28 is a side perspective view of yet another alternative embodimentto anchor the retractor to the patient pad.

FIG. 29 is a side perspective view of a retractor including a handle tomanually stabilize the retractor in the patient.

DETAILED DESCRIPTION OF THE INVENTION

The present invention is directed to methods and devices for performingpercutaneous surgery and in particular spinal surgery. The surgery isperformed through a portal or passageway provided by a retractor. Theretractor is expandable in situ to thereby increase the size of thesurgical area as well as the access thereto. It is particularlyconstructed to minimize trauma to tissue surrounding the retractor andthe surgical area. The retractor can be used with any surgical approachto the spine such as; lateral, postero-lateral and/or antero-lateral,anterior, posterior, posterior mid-line, and in other regions of thebody not associated with the spine.

FIG. 1 is a top view of retractor 1. As shown retractor 1 is comprisedof four discrete segments. As shown, the segments consist of a pair ofopposing semi cylindrical members 4A and 4B as well as a pair ofopposing semi elliptical members 6A and 6B. A ratcheting mechanism 8Aand 8C is located at each of the junctions between opposing semicylindrical member 4B and opposing semi elliptical members 6A and 6B.Likewise a ratcheting mechanism 8B and 8D is located at each of thejunctions between semi cylindrical segment 4A and opposing semielliptical members 6A and 6B. The four segments once assembled andsurrounded by a silicone sleeve 10 form a single working unit that isgenerally elongated and oval shaped in cross section. The sleeve 10conforms to the shape of the exterior surfaces of the segments andextends the entire length of the segments from the proximal end, the topportion, to the distal end, bottom portion and exerts a radiallydirected inward force against segments 4A, 4B, 6A and 6B. The assemblythereby forms an elongated ovoid shaped retractor wherein the paralleldistraction will occur along the length of the retractor based upon theengagement and disengagement of the teeth placed along the longitudinalaxis of the retractor. While shown and described as having four segmentsthe retractor could be formed as two segments each including a semicylindrical segment and a semi elliptical segment.

The segments 4A, 4B, 6A and 6B are formed from plastic or any othersuitable radio lucent material. Segments 4A and 4B each respectivelyhave screw holes 12A and 12B designed to receive a bone screw for distalfixation of the retractor to a vertebral body. The segments also containinsulated electrical conductors 16 included in the walls of thesegments. The conductors 16 terminate at the proximal and distalsurfaces of the segments with exposed electrical contacts to provide anelectrical pathway for nerve monitoring Also included within thesegments are internal tracks for mounting fiber optical lights 18 toprovide illumination of the surgical space located at the distal end ofthe retractor. Each of the segments 4A, 4B, 6A, and 6B may contain radioopaque markers 24 to enable visualization throughout the procedure.

FIG. 2 shows a partially exploded top view of the four segments prior toengagement via the ratcheting mechanisms. FIG. 3 is an enlarged view ofthe encircled area of FIG. 2. As can be seen in FIG. 3 semi-circularsegments have teeth or grooves 20 located on the interior surfaceadjacent both edges of the semi circular segments 6A and 6B. These teethor grooves 20 are located at four separate points along the length ofthe segments between the proximal and distal end portions as shown inFIG. 5. Alternatively teeth or grooves 20 can run the entire length ofthe segments from the distal end portion to the proximal end portion asshown in FIG. 6. As seen from the front view, the lower distal endsurface of segments 6A and 6B form a concave edge 26. FIG. 7 shows aside view of the external surface of the semi cylindrical segments 6Aand 6B. FIG. 8 is a front view of the exterior surface of one of thesemi elliptical members 4A and 4B. As seen from the front view the lowerdistal end surface of segments 4A and 4B form a convex edge 28. Concaveedges 26 and convex edges 28 form a tip at the distal end of theretractor 1 that is anatomical in shape and particularly configured tosignificantly improve the ability to mobilize, dissect, split andretract the terminal tissues of the psoas muscle at the point on thespine where the entry is to be made. FIG. 9 is an exterior surface sideview of one of the semi elliptical members 4A and 4B. One or both of thesegments 4A and 6B contain an insulated electrical conductor 16 includedin the walls of the segments. A tool 30, shown in FIGS. 11A and 11B isused to facilitate a ninety degree rotation of the retractor as will beexplained below. The tool 30 includes a pair of diametrically opposedhandles 32 and 34 that are each connected to an annular member 36. Theinner surface 38 of the annular member 36 is configured to operativelycooperate with the external surface of sleeve 10 surrounding theretractor 1 adjacent the top portion thereof. Semi elliptical segments4A and 4B have complimentary teeth or grooves 22. Teeth or grooves 22are located on the exterior of semi elliptical segments 4A and 4Badjacent each of the edges of semi elliptical segments 4A and 4B. Teethor grooves 22 extend the entire length of the segments form the proximalto distal end portion as shown in FIG. 9. FIG. 4 shows one of theratcheting mechanisms 8A-8D and the inter engagement of teeth 20 and 22as well as sleeve 10 which exerts a radially directed inward force oneach of the retractor segments.

The present system is a patient based retractor that does not requirefixation to an articulating arm. The patient based retractor includes apad 40 that eliminates the necessity for a rigid fixation to a pointoutside of the field of operation or to an independent immobile pointsuch as a bed rail. The pad 40 is applied to the sterilized area on thepatient's body 41. The physical properties of the material including itssize, thickness and composition cause significant friction, or adhesion,between the pad and the sterile site on the patient's skin. By way ofexample, FIGS. 10A and 10B illustrate the pad 40 in a deployed position.This can be reinforced with the application of tape and or IOBAN® ifnecessary. By way of example the pad can be formed from a polyurethanematerial. While the pad 40 and retractor 1 have been shown for useduring minimally invasive spinal surgery it should be understood thatthe anchoring pad 40 could be used in combination with retractor 1 or aretractor of any configuration and for other types of surgery as well,such as laparoscopic gal bladder surgery or appendectomy.

The tube retractor technique starts with identifying the correct entrypoint, and correct trajectory from the skin to the pathology to beaddressed. A top view of the incision 42 is shown in FIG. 10B. Theinitial soft tissue cannulated dilator 50 of circular cross section, asshown in FIG. 12A, is inserted through the incision and forcefullyadvanced to the objective site. A series of larger diameter dilators asshown in FIG. 12B, 51 and 52, are inserted over the initial dilatorsequentially increasing in diameter until the final operative diameteris inserted. The final operative dilator 54 is oblong in cross sectionas is shown in FIG. 12C through 12F. FIG. 12C is a front perspectiveview of the ovoid shaped final dilator. FIG. 12D is a side view of thebottom or distal end surface 56 of the final dilator that is convex inshape on both side wall portions. FIG. 12E is a perspective bottom viewof the bottom or distal end surfaces of the final dilator that shows thefront and back wall surfaces having bottom edges 58 that are concave inshape. The two convex surfaces at the lower edge of the side wallportions and the concave edges on the front and back walls form a distalor end surface that is anatomical in shape and particularly configuredto significantly improved the ability to mobilize, dissect, split andretract the terminal tissues of the psoas muscle at the point on thespine where the entry is to be made. Once in its proper position theoblong operative dilator 54 is rotated ninety degrees and then counterrotated back to its original position using the tool 30. FIG. 13 is atop view of the retractor in position on the patient. FIG. 14A is a topview of the retractor 1 in position within the patient's body and FIG.14 B is a side view of the retractor within the patient's body 41. Asshown in FIGS. 14A and 14B the spinal disc 60 is located betweenvertebral bodies 62 and 64. As shown, each vertebral body includes aspinous process bone 66 and a pair of pedicle bones 68. Either segment6A or 6B can be seen in this view. Once in this position, the retractor1 is then rotated ninety degrees using tool 30 to the position shown inFIG. 15. FIG. 15 is a top view of the retractor 1 in position on thepatient after being rotated. The shape of the distal end of theretractor segments provides a significant improvement in the ability tomobilize, dissect, split and retract the terminal tissues of the psoasmuscle at the point on the spine where entry is to be made. Currentdesigns are parallel to the spine and do not comply with the naturalshape of the spine, thereby allowing the terminal psoas muscle fibers tocreep under the retractor and completely undermine the process and inmany cases reduces the overall success and intention of the minimallyinvasive technique. The ninety degree rotation of the retractor 1enables the distal portions of the psoas muscle to be mobilized andretracted via the retractor. This action reduces muscle creep therebyreducing the necessity for the surgeon to cut, cauterize and removemuscle fibers to access to the pathology.

Once the retractor 1 is rotated into final position the final andinitial dilators are withdrawn from the patient. At this point, a seriesof retractor expansion dilators, shown in FIG. 12 C, are available forexpansion of the retractor 1. These expansion dilators are cannulatedand assist in centering the retractor with the initial k-wire that isalready in place. The expansion dilators are 14, 16, 18 and 20 mm indiameter. As progressively larger expansion dilators are inserted withinthe retractor 1, segments 4A, 4B, 6A and 6B move relative to one anotherby virtue of ratcheting mechanisms 8A, 8B, 8C and 8D. By way of example,it is contemplated that the distance between segments 4A and 4B at theirmid points can be increased from 14 mm to 18 mm and the distance betweensegments 6A and 6B at their mid points can be increased from 18 mm to 22mm, as shown diagrammatically in FIGS. 17A and 17B. At this point theexpansion dilators are removed and the operation can proceed. Theretractor is anchored at the near portion by frictional engagement withpad 40. In addition the retractor 1 may be anchored at the distal endportion using bone screws that are inserted through holes 12A and 12B ofthe retractor and threaded into the vertebral body. The pad 40eliminates the need for a rigid fixation to a point outside the surgicalfield or to an independent fixed point such as a bed rail. Theelimination of these metallic supports that are typically associatedwith minimally invasive tube or split blade retractors increases thevisualization of the approach through the retractor and visualization ofthe surgical site while using operative fluoroscopy.

The retractor system of the present invention was developed to provideminimally invasive access to a patient's pathology. The ability todilate muscle tissue, as opposed to the process where the muscle tissueis stripped or detached from the skeletal structure will usually reducethe morbidity associated with the standard invasive technique. Theprocedure utilizing the retractor system of the present invention startswith the identification of the correct entry point, the propertrajectory from the skin to the pathology to be addressed as well as thepoint of incision. After the initial incision has been made through thepatient based anchoring pad and into the skin the initial soft tissuedilator is inserted through the incision and forcefully advanced to theobjective site. The initial dilator is 6 mm in diameter and round incross section. Thereafter, a series of progressively larger dilators areinserted over the initial dilator; increasing in diameter until thefinal operative dilator is inserted. The final operative dilator isoblong in cross section. Once the final operative oblong dilator is inplace it is then rotated ninety degrees by tool 30 and then counterrotated ninety degrees back to its initial position. The retractor 1 isthen placed over the final operative dilator and forcefully advanced tothe objective site. Once in position the retractor is then rotatedninety degrees by using a tool 30. Thereafter the initial and finaldilators are removed. Following removal of the dilators used for initialdelivery, a series of expansion dilators, are inserted into the centerof the retractor 1 to expand the open area or portal within theretractor. These expansion dilators are circular in cross section andrange in diameter from 14 mm to 20 mm. As the expansion dilators areinserted the ratcheting mechanisms 8A, 8B, 8C, and 8D allow relativemovement between the adjacent retractor segments by virtue of thedisengagement and reengagement of the teeth 20 and 22. The expansiondilator creates a force directed radially outwards thereby causing ashift in the alignment of teeth 20 and 22. Simultaneously resilientsleeve 10 exerts a radially inward directed force maintaining the teeth20 and 22 in their newly established position.

FIGS. 18A, 18B, 18C and 18D illustrate various views of an alternativeembodiment for the oblong final operative dilator. As shown in theseviews the final operative dilator 154 includes an upper, proximate, edge156 and a lower, distal, edge 158. The dilator includes a centralpassageway 160 that is generally cylindrical in cross section andextends the entire length of the dilator 154 from the upper edge 156 tothe lower edge 158. The outer surface of the dilator 154 generallyconforms to the inner surface of the retractor- and includes a pair ofopposing semi elliptical surfaces 162A and 162B as well as a second pairof opposing semi elliptical surfaces 164A and 164B which together form acontiguous outer surface of the final operative dilator 154. The upperedge surface 156 is generally planar and formed orthogonally withrespect to the outer surface of the retractor. The lower distal edge 158is formed from a plurality of thin arcuate surfaces forming a concaveshape at the distal end of the dilator. The walls of the distal endportion are tapered to form this series of thin arcuate surfaces. Thearcuate surfaces includes a pair of curved surfaces 166A and 166Bproximate the distal ends of semi elliptical surfaces 162A and 162B.Surfaces 166A and 166B are connected at a point 168 located at the mostdistal end of the dilator. Formed on the lower distal edge surface 158adjacent opposing semi elliptical surfaces 164A and 164B are curvedsurfaces 170 and 172. Each of the curved surfaces 170 and 172 has afirst and second ends connected to the curved surfaces 166A and 166B.The mid point of surfaces 170 and 172 being located closer to the uppersurface of the final dilator. The lower distal edge 158 thereby formingan anatomically concave shape at the tip of the dilator. The concaveshaped distal end extends over the disc/endplate interface. The concaveshape will gently divide the muscle and fiber tissue. The anatomicallycurved distal tip of the dilator gently separates the final psoas fibersdirectly attached to the interverbral disc/vertebral body interfacealong the lateral aspect of the spine. This gentle splitting of thefibers occurs along the same plane as the muscle fibers which ensure asplit/separation action. By mobilizing a longer axis of muscle fibersthe forces normally associated with larger dilators are applied along agreater surface area of tissue which reduces the forces directlyassociated with the immediate surrounding tissues and of greaterconsequence, the neural tissues such as the lumber plexus. Once thefibers have been split along the length of the muscle a gentle rotationof the dilator gently sweeps the terminal fibers attached to the lateralaspect of the intervertebral disc. This enables the tissues to be sweptand subsequently maintained outside the working area once the retractoris placed and rotated into its final working position. This action willresult in a less disruptive means of exposure thereby reducing the needfor cutting or electro-cauterizing the final fibers while providingbetter visualization of the target area of surgery.

Current dilators and retractors use a cylindrical design with a flatplanar surface. They rely on compression of the fibers at the distalaspect of the device to achieve dilation. Typically retractors usecompressive forces, sequentially, to distract a parallel opening whichincreases muscle disruption and potential nerve compression. Thisarrangement allows for the final fibers to creep under the edges of theretractor and does not allow for sweeping of the final fibers. When thetypical retractor is opened with the final fibers still intact withinthe target area for surgery, they will need to be moved with instrumentsthat makes the process, tedious and increases the risk of neural andvascular structures being unintentionally cut or crushed as the fibersand tissue are cut, torn and/or electro cauterized.

FIGS. 19A, 19B, 19C, 19D and 19E illustrate various views of anotheralternative embodiment for the oblong final operative dilator. As shownin these views the final operative dilator 254 includes an upper,proximate, edge 256 and a lower, distal, edge 258. The dilator includesa central passageway 260 that is generally cylindrical in cross sectionand extends the entire length of the dilator 254 from the upper edge 256to the lower edge 258. The outer surface of the dilator 254 includes apair of opposing semi elliptical surfaces 262A and 262B as well as asecond pair of opposing semi elliptical surfaces 264A and 264B whichtogether form a contiguous outer surface of the final operative dilator254. The distal end of dilator 254 includes concave outer surfaces thatextend outwards in a curved fashion from the semi elliptical surfaces262A, 262B, 264A and 264B. Concave surface 263A extends radially outwardfrom surface 262A. Concave surface 263B extends radially outward fromsurface 262B. Concave surface 265A extends radially outward from surface264A and concave surface 265B extends radially outward from surface and265A. The upper edge surface 256 is generally planar and formedorthogonally with respect to the outer surface of the dilator. The lowerdistal edge 258 is formed from a plurality of thin arcuate surfacesforming a concave shape at the distal end of the dilator. The walls ofthe distal end portion are tapered to form this series of thin arcuatesurfaces. The arcuate surfaces includes a pair of curved surfaces 266Aand 266B proximate the distal ends of semi elliptical surfaces 262A and262B. Surfaces 266A and 266B are connected at a point 268 located at themost distal end of the dilator. Formed on the lower distal edge surface258 adjacent opposing semi elliptical surfaces 264A and 264B are curvedsurfaces 270 and 272. Each of the curved surfaces 270 and 272 has afirst and second ends connected to the curved surfaces 266A and 266B.The mid point of surfaces 270 and 272 being located closer to the uppersurface of the final dilator. The lower distal edge 258 thereby formingan anatomically concave shape at the tip of the dilator. The concaveshaped distal end extends over the disc/endplate interface. As finaloperative dilator 254 has a distal end that includes concave outersurfaces that extend outwards in a curved fashion from the semielliptical surfaces 262A, 262B, 264A and 264B it will be removed fromthe incision after its insertion and the aforementioned rotation priorto insertion of the retractor. The configuration of the final operativedilator 254 will split the psoas muscle in the same manner as describedwith respect to final operative dilator 154.

FIG. 20 is a perspective view of an alternative embodiment of theadjustable retractor 300. Retractor 300 is an elongated body that ismade up of a plurality of selectively engaging segments. The segmentsinclude a first pair of elongated members 302A and 302B having opposedsemi elliptical shaped cross section and a second pair of elongatedmembers 304A and 304B having opposed semi elliptical shaped crosssection. Each segments has a top, or proximate, portion and a bottom, ordistal, portion. The length of the elongated members being of a lengthto span the distance from adjacent the surgical area at the distal endportion to a location external to the patient. The distal end of theretractor 300, comprised of the distal ends of elongated members 302A,302B, 304A and 304B, has the correct concave shape to allow for moreeffective dissection of the terminal tissues at the distal end of theretractor 300.

FIG. 21 is a top view of the retractor shown in FIG. 20 with theretractor in its most compact configuration. As can be seen in thisview, elongated members 302A and 302B have step like teeth 306 and 308that are directed radially inward while elongated members 304A and 304Bhave complimentary teeth 310 and 312 that are directed radially outward.Teeth 306 and 308 on members 302A and 302B and teeth 310 and 312 onmembers 304A and 304B generally run the length of the retractor from theproximate to the distal end. The elongated members are retained in afixed position under the influence of elastomeric bands 301 that exert aradially directed inward force. Three elastomeric bands are shown inFIG. 20, by way of example, recognizing that more than three or lessthan three can be used as well. The elastic bands provide the tensionnecessary to maintain multiple pieces together during initial insertionof the dilator. They also provide the appropriate amount of tensionrequired to allow sequential dilation/opening of the retractor inparallel fashion along the length of the retractor. This aspect of theinvention eliminates a problem associated with current retractorswherein the application of dilating force at the proximal end toovercome the physiological forces applied to the human anatomy at thedistal end results in a larger opening proximally with little effect anda smaller opening distally. This problem runs counter to the overallobjective of minimally invasive proximal openings with minimaldisruption of the terminal fibers at the intended surgery target area.

FIG. 22 is a top view of the retractor shown in FIG. 20 with a retractordilator expanding the retractor an intermediate expanded configuration.As can be seen in this view, as a first retractor dilator 314 isinserted into a cavity formed within the assembly of elongated members302A and 302B are urged radially apart from one another therebydisengaging the step like teeth on the elongated members. At the sametime the first retractor dilator 314 urges the elongated members 310 and312 radially outward. Upon removal of the first retractor dilator 314the retractor 300 has been reconfigured to an intermediate position asshown in FIG. 23 wherein the elongated members 310 and 312 have movedradially outward to the next step on elongated members 302A and 302B.Upon removal of the retractor dilator the elastomeric bands 301 willagain exert a radially directed inward force and maintain engagement ofthe teeth on the elongated members, as shown in FIG. 23.

FIG. 24 is a top view of the retractor of FIG. 20 with a secondretractor dilator urging the retractor to the most expandedconfiguration. The second retractor dilator 316 is larger than the firstretractor dilator 314. As the second retractor dilator 316 is insertedinto a cavity formed within the assembly of elongated members, members302A and 302B are urged radially apart from one another therebydisengaging the step like teeth on the elongated members. At the sametime the second retractor dilator 316 urges the elongated members 310and 312 radially outward. Upon removal of the second retractor dilator316 the retractor 300 has been reconfigured to a final position as shownin FIG. 24 wherein the elongated members 310 and 312 have moved radiallyoutward to the next step on elongated members 302A and 302B. Theelastomeric bands 301 will again exert a radially directed inward forceand maintain engagement of the teeth on the elongated members, as shownin FIG. 24.

FIG. 25 is a perspective top view the retractor, the patient pad 400 anda device to anchor the retractor to the patient pad. Patient pad 400 issimilar to pad 40, as described above, but further includes a hard ring402, formed from metal or plastic, surrounding the retractor 300 thathas been placed through the pad 400. A pair of tabs 404 extends from theproximal end of the retractor. The material for the tabs 404 is a moremalleable composite of the material used for the retractor. The tabs 404include holes or slots 406 that are configured to receive threaded thumbscrews 408. Likewise, ring 402 includes holes and or slots 410 locatedaround the circumference of the ring 402. Thumb screws 408 are passedthrough the appropriate apertures 406 in tabs 404 and are secured in theappropriate apertures 410 located on ring 402. The tabs can bepositioned at the desired location along the ring. Then the thumbscrewsare are positioned in the proper apertures and tightened, whereby thetabs will hold the proximal end of the retractor at the desired angle.

FIG. 26 is a perspective view an alternative arrangement for anchoringthe retractor 300 to the patient pad 400. In this embodiment theretractor 300 has a pair of radially projecting tabs 420 that areoriented in diametrically opposed relationship. Patient pad 400 includesan annular recess or groove 422 formed either within or recessed on thebottom side of the pad. Located on the upper surface of patient pad 400is a pair of diametrically opposed slots 424 that extend from the uppersurface to the groove or recess 422. To anchor the retractor, each ofthe tabs 420 is brought into alignment with a slot 424. After each tab420 is positioned within groove 422 the retractor is rotated withrespect to the pad thereby effectively anchoring the retractor 300.

FIG. 27 is a perspective view of another alternative embodiment toanchor the retractor to the patient pad. In this embodiment tabs 440extend from the proximal aspect of the retractor 300 in diametricallyopposed orientation. The tabs 440 are made from a malleable plasticmaterial. As shown in FIG. 27 the tabs fold along the edge of theretractor 300 and the pad 400 is placed over the retractor 300. Theretractor extends through the pad 400 through a slit formed thereinwhile the tabs are positioned beneath the pad 400. The tabs maintain adownward force on the retractor with the constant pressure applied fromthe patient pad that is in contact with the patient's skin.

FIG. 28 is a perspective view of yet another alternative embodiment toanchor the retractor to the patient pad. In this embodiment the proximalaspect of the retractor 300 includes a series of coarse threads 452formed on the exterior surface of the retractor. The patient pad 400includes ring 454 embedded in the upper surface of the patient pad 400.The exterior surface of ring 454 includes thread 456 configured with thesame coarse thread dimension as threads 452. An internally threadedannular ring 450 is used to secure the retractor to the patient pad. Theinternal threads of annular ring 450 are sized and configured tothreadably engage threads 452 on the retractor and thread 456 on theembedded ring 454. The retractor is placed through an opening in pad 400and the annular ring 450 is placed over the retractor 300. As the ringis tightened it applies a downward force to the retractor's proximal endto maintain the desired depth of the distal tip in the patient's tissue.

FIG. 29 is a perspective view of a retractor including a handle tomanually stabilize the retractor in the patient. In this embodiment theproximal aspect of the retractor 300 cooperates with a manual anchoringdevice that includes an annular member 464 with a pair of diametricallyopposed arms 460 extending radially outward from annular member 464. Thebottom surface of annular member 464 includes an annular groove 466.Annular groove 466 is comprised of a series of semi elliptical segments,configured to mate with the upper surface of the retractor 300, andhaving sufficient width so as to be able to cooperate with the upperperipheral edge of retractor 300 either in its compact, intermediate orexpanded condition. Arms 460 and annular member 464 are formed from arigid material such as a rigid plastic or metal. Each arm includes agripping element 462. As shown, the gripping element is a ball typehandle however any other type of handle mechanism such as a verticalpost, or “T” or loop configuration would be acceptable. The retractor300 would be physically stabilized by an individual grasping and holdingeither one or both of the gripping elements 462 in a fixed position.Alternatively, one could use the hand stabilized retractor without theaid of the patient pad 400.

All patents and publications mentioned in this specification areindicative of the levels of those skilled in the art to which theinvention pertains. All patents and publications are herein incorporatedby reference to the same extent as if each individual publication wasspecifically and individually indicated to be incorporated by reference.

It is to be understood that while a certain form of the invention isillustrated, it is not to be limited to the specific form or arrangementherein described and shown. It will be apparent to those skilled in theart that various changes may be made without departing from the scope ofthe invention and the invention is not to be considered limited to whatis shown and described in the specification and any drawings/figuresincluded herein.

One skilled in the art will readily appreciate that the presentinvention is well adapted to carry out the objectives and obtain theends and advantages mentioned, as well as those inherent therein. Theembodiments, methods, procedures and techniques described herein arepresently representative of the preferred embodiments, are intended tobe exemplary and are not intended as limitations on the scope. Changestherein and other uses will occur to those skilled in the art which areencompassed within the spirit of the invention and are defined by thescope of the appended claims. Although the invention has been describedin connection with specific preferred embodiments, it should beunderstood that the invention as claimed should not be unduly limited tosuch specific embodiments. Indeed, various modifications of thedescribed modes for carrying out the invention which are obvious tothose skilled in the art are intended to be within the scope of thefollowing claims.

What is claimed is:
 1. An operative dilator having an elongated body,said elongated body having a length spanning the distance above apatient's skin surface at a proximal end portion and juxtaposed asurgical area at a distal end portion, said operative dilator beingoblong in cross section, said distal end portion having walls that taperinto a thin distal end surface, said distal end surface having a pair ofoppositely opposed concave surfaces joined by a pair of oppositelyopposed convex surfaces.
 2. The operative dilator of claim 1 wherein anexternal on said elongated body adjacent the proximal end portion isconfigured to receive a hand tool whereby the dilator can be rotatedninety degrees, said rotation enabling the distal end surface to safelyand gently sweep the terminal fibers thereby enabling consistentretraction of the muscle fibers while a retractor is inserted.
 3. Theoperative dilator of claim 1 wherein the outer surfaces of said distalend portion is comprised of a plurality of concave surfaces that extendradially outward from the other outer surfaces of the elongated body.